9405552 Weldon This research is to determine the size, extent, and timing of historic and recent surface ruptures associated with the Xianshuihe Fault in Sichuan Province, China. Preliminary work by U.S. and Chinese scientists reported at a conference in Chengdu, September 1990, and in the subsequent literature, indicate that it would be possible to document the ages, distribution, and magnitude of slip associated with recent ruptures to test the hypotheses of fault behavior. Excellent geomorphic evidence for multiple ruptures is preserved in many areas, and trenches described by Chinese scientists, and one briefly visited during September 1990, contain good microstratigraphic evidence for the timing and size of events. This study will add to the extremely limited data set for large strike-slip ruptures so that we can better understand how "characteristic" ruptures on large faults really are. Such empirical observations of fault behavior are critical for prediction efforts and for understanding the underlying physics of rupture processes. This research is a component of the U.S.-P.R.C Protocol on Earthquake Studies and the National Earthquake Hazard Reduction Program. ***
